Mark Sullivan, senior director of the Secret Service, is looking into the report but has so far not found anything “credible” to back it up, Representative Elijah Cummings, the top Democrat on the House Oversight and Government Reform Committee, said outside the US House of Representatives.

The allegations arise from a television interview, in which an anonymous US contractor described visiting a San Salvador strip club that offers sexual favours with some Secret Service agents and US military specialists in advance of Obama’s March, 2011, visit.

The report said high-ranking US embassy employees also “routinely” visited the strip club.

“Obviously, we will inquire of our embassy in San Salvador with regard to the conduct of our own employees. But the article alleges that they attended the establishment, not that they engaged in any illegal or unsanctioned conduct,” Victoria Nuland, US state department spokeswoman, said.

New prostitute claim

US officials are also facing charges from a Brazilian prostitute who is set to sue the US embassy and five staff members, including three members of the United States Marine Corps.

Romilda Aparecida Ferreira, described as a “sex professional and dancer” by her lawyer, plans to sue for injuries, medical expenses, and lost income sustained after she was allegedly pushed out of a moving van in the Brazilian capital, Brasilia.

Ferreira’s lawyer, Cezar Britto, says she and three other women left with the men in three vehicles after a night out at a nightclub on December 29, 2011.

Britto says a soldier tossed his client from the vehicle following an argument, leading Ferreira to break her collarbone, two ribs, and puncture a lung.

The US state department says the woman was outside, trying to open the moving vehicle’s door.

The four Americans were sent home.

The allegations come a week after revelations that agents were involved with prostitutes before a presidential visit to Cartagena, Colombia, for the Summit of the Americas.